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  1. Martinos

    Cracking a carburising pieces

    In fact, welding of carburized components is not the best idea, but if it works in the past, then okay. Anyway, I really don't assume case depth 0,3 mm instead of 0,25 mm plays a role there. As EdStainless wrote, I would suspect welding process. Also, check (case and core) microstructure and...
  2. Martinos

    Trouble with Heat Treatment of 1022 steel Fasteners

    Carburizing or carbonitriding. That is the purpose of this grade.
  3. Martinos

    modifying ASTM A536 ductile iron standard material Grades

    Do not be worried. We are working here with EN-GJS-700-2 ductile cast iron commonly, also we are doing induction hardening process in some cases and there is no problem even elongation looks terrible. Based on elongation level it may looks way too brittle, but it is not as terrific as it seems...
  4. Martinos

    increasing tensile strengthn of 4140 steel shaft 7ft

    Hi, jawdayub1, definitely you can buy the bars at 35-40 HRC and do the knurling after. It is very common (and effective) to buy prehardened bars and do machining operations after. QT condition 35 - 40 HRC is not such a terrific regarding machinability, but yes, it is not machinability level like...
  5. Martinos

    How Martensite forms in low carbon SS like A743 gr. CA6NM? And why not then in Ferritic grades of SS

    Hi, Abhijeet242. In that case never mind carbon as such. It is mainly about chromium content, but also carbon and other elements are connected. There is some theoretic equation about stainless steel hardenability:
  6. Martinos

    1.4849 tensile failure

    36% nickel content means not pores, but shrinkage could be a problem. Is necessary to see fracture surface exactly. Macro and micro. Micro you showed to us looks OK, but maybe I want to see more uniform interdendritic distribution of M23C6 carbides. You have here 2 types of carbides Cr-rich...
  7. Martinos

    Stainless alternatives to 42CrMo4

    I recmmend you to focus to martensitic stainless steels group as X46Cr13, X30Cr13 or X17CrNi16-2.
  8. Martinos

    Effect of microstructure on induction hardening steel

    Of coarse, sorbitic QT (core) microstructure is the greatest basis for surface hardening, but: a) specimen A is definitely not in QT state, is coarse and acicular (Widmanstätten) this does not belong to proper austenitising, quenching and high tempering : definitely not sufficient...
  9. Martinos

    Effect of microstructure on induction hardening steel

    Hello. I have read your discussion and I have to write that the origin of the acicular structure is what I am interested in. Hardness level about 220 HV? Definitely ferrite and pearlite, but why coarse acicular? Standard hardening and high temperature tempering? I do not know why the result...
  10. Martinos

    304Cu steel microstructure

    Ed, Ben, please, take a look at some photomicrographs after Beraha tint etching.
  11. Martinos

    304Cu steel microstructure

    Ed, At this time I have no possibility to electrolytic etching, but regarding oxalic acid I share your opinion. Coincidentally I am going to try color tint etch with Beraha. A few hours ago I have ordered potassium metabisulfite to our lab. I will post some photos after.
  12. Martinos

    304Cu steel microstructure

    Ben, I understand that material was cold worked after solution annealing (see attachment). How much cold work? I have no idea. Irony, SEM more likely than TEM may be helpful in a special cases, e. g. where the chemical composition of complex carbides is important (gasoline turbocharger VTG...
  13. Martinos

    304Cu steel microstructure

    Yes. SEM/TEM may be helpful. This strain induced needles were not found in the past, til now and along with this we have some problems with deformations - residual strains after machining of bars. I think there are some changes in drawning process from side of our supplier (of course they say...
  14. Martinos

    304Cu steel microstructure

    Yes. I think you could have a truth. I think to myself what can 3% of copper do. Some can be dissolved in austenite, but some not - where is it?. Unfortunately, I do not have a better laboratory necessaries to have more precise analysis. Thank you for great discussion guys.
  15. Martinos

    304Cu steel microstructure

    Ben, Ed, I have no possibility to electrolytic etch, but please take a look at the pictures linked below. After re-polishing only a few (Cr)MnS inclusions were found. But these photomicrographs linked below are after another etching this time with waterless Kalling's2 up-to 20 seconds. In my...
  16. Martinos

    304Cu steel microstructure

    1. Kalling's 1 (Kalling's with water) 2. Original magnification 500, but camera magnified itself and make it almost 2x original magnification 3. I will check the magnetism - on tuesday. But I assume delta ferrite is magnetic as well as martensite (?) 4. sulphur 0.02%, definitely the stringers...
  17. Martinos

    304Cu steel microstructure

    Hi dudes. I have here drawn bar made of 304Cu (1.4567) steel in solution annealed condition. Chemical composition C 0.011 Si 0.40 Mn 0.75 S 0.02 Cr 17.1 Mo 0.32 Ni 8.6 Cu 3.1%. Please take a look at a photomicrographs linked below (1x transverse cut, 2x longitudinal cut). I have a dispute...
  18. Martinos

    Brass state

    Hi guys, anybody knows what means designation F36, F43 or F49 reported as a state of brass semi-product? Thank you for yout answer. Martinos.
  19. Martinos

    Antimony in heat resistant steel castings

    @metengr, definitely ferro-niobium, because antimony content is correlating with niobium content... spectral lines were checked by specialist, it is not an influence of niobium spectrum, but real antimony content... it looks like we have antimony content higher for a while in all our alloys...
  20. Martinos

    Antimony in heat resistant steel castings

    They are vane rings or discs in turbocharger assemblies. Corrosion test were not carried out. Mechanical properties of ferritic casting: Rm 290 MPa (shall be 450 MPa), Rp0,2 unmeasurable (shall be 400 MPa). Elongation unmeasurable (shall be 5 %). The fracture was very brittle. Grades are...

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